Finding the Fourth Proportional to 1,382.30, 1,907.40 and 784.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,382.30 : 1,907.40 = 784.78 : x
2. Step 2: Convert to fraction form
   1,382.30/1,907.40 = 784.78/x
3. Step 3: Cross multiply
   1,382.30x = 1,907.40 × 784.78
4. Step 4: Simplify right side
   1,382.30x = 1,496,889.37
5. Step 5: Solve for x
   x = 1,496,889.37/1,382.30
6. Step 6: Final answer
   x = 1,082.90